The Reciprocal Association between Fitness Indicators and Sleep Quality in the Context of Recent Sport Injury

The purpose of the study is to investigate whether the oxygen uptake and heart rate at rest, in Greek professional soccer players, are affected by recent injuries, as well as how sleep quality is affected. Forty-two male professional soccer players were included in the study and divided into two groups: injurygroup (n = 22, age: 21.6 ± 5.4 years, body fat: 11.0 ± 3.9%, total body water: 64.0 ± 2.5%) and no-injurygroup (n = 20, age: 24.2 ± 5.6 years, body fat: 10.1 ± 2.8%, total body water: 64.3 ± 1.8%). The oxygen uptake at rest (VO2resting, mL/min/kg) and heart rate (HR, bpm) were recorded in the upright position for 3 min, and the predicted values were calculated. One hour before, the athletes answered the Pittsburgh Sleep Quality Index (PSQI) questionnaire. The results showed a difference between groups (injurygroup vs. no-injurygroup) in VO2resting (7.5 ± 1.4 vs. 5.5 ± 1.2 mL/min/kg, p < 0.001) and percent of predicted values (92.5 ± 17.2 vs. 68.3 ± 14.6%, p < 0.001) and HR, such as beats per min (100.6 ± 12.8 vs. 93.1 ± 4.6 bpm, p = 0.001), percent of predicted values (50.7 ± 6.4 vs. 47.6 ± 2.8%, p = 0.003) and sleep quality score (PSQI: 4.9 ± 2.2 vs. 3.1 ± 0.9, p = 0.005). Anthropometric characteristics were not different between groups. Oxygen consumption and heart rate at rest are affected by the systemic adaptations due to injury. These pathophysiological changes probably relate to increased blood flow in an attempt to restore the injury area.